Rear end gear advice

2847 Views 15 Replies 11 Participants Last post by DROPTOPtimes2, Mar 22, 2007

Original68fromauntsgarage

Discussion Starter · Mar 21, 2007

Hey all;

I wanted to ask for some advice from the bunch please;

I have a 1968 Camaro that has factory 2:73 gears in the rear.

Ya, I know, OH GOSH!!!!! Kind of like running with a cast....pretty slow.....

Anyhoo, I am curious, what kind of gears can I get in there; My goal is about a 3:55 or so as I would like to have a ratio that will work well with an M20 tranny, but not over tach on the highway, and still, have some get up and goon the street....ya, ya I know 5 speed tremec.....but I want a muncie!!!

So the question is do I need a new carrier, or can I get in some gears with the rear I have now?????

Any advice on this topic is highly appreciated!

Thanks a lot,

Don

1 - 16 of 16 Posts

DOUG G

· #2 · Mar 21, 2007

Yes, you'll need a 3 series carrier. You can't get anything better on the carrier you have now... maybe with a spacer, which I don't like.

I miss my 2.73's and 80mph in 1st playing with ricers (best ET was [email protected] with the 2.73's

)

Original68fromauntsgarage

Discussion Starter · #3 · Mar 21, 2007

So then are you saying that the 2:73s may not be so horrible???? It has been a while since I have played with cars and am a bit rusty.........

So let me pose this direction; If YOU had a an M20 and 2:73 gears what would you do?????

Thanks.............................

JimM

· #4 · Mar 21, 2007

If I had an M20 and 2.73 gears, I'd..... buy a TKO500!!!!
That 3.27 low will wake the 2.73's right up!

CRASH69

· #5 · Mar 21, 2007

I used to have a 73 Z28 450HP smallblock with a M20, I put 343's in the rear. It was a great street & strip car and was decent on the highway, I had that combo for 3 years then sold the car, Other freinds of mine had 355's with the M20 They were also happy with that combo. Crash

big gear head

· #6 · Mar 21, 2007

It's going to be a little hard to get moving with a 4 speed and 2.73 gears. Assuming that this is the 8.2 10 bolt, the 3.36 would be a good choice in my opinion if the car will see much highway use. The 3.55 would be great if you don't ever leave town, or for short trips from time to time. You will need a 3 series differential. I recommend the new 3 series Eaton posi. You will also need a good installation kit.

Straight-line-69

· #7 · Mar 21, 2007

If you're running a 27" tire you could go 3.73 with your M-20. Not great for long highway trips but a blast in town. Your tach will show about 3000 rpm at 60 mph.

What cam are you running?

go2fast

· #8 · Mar 21, 2007

I had 2.73s in my 327/M20 for a while. It was slow and hard on the clutch. I changed it to 3.23s (8.5" diff) and it's much better. Not lightening quick off the line, but I run about 2600RPM at 65MPH. It's a good trade off for me.

mikes69z

· #9 · Mar 21, 2007

A 2.73 rear is a perfect match for a Doug Nash 4+1 (Richmond street 5 speed). With the 3.27 first gear in that trans it will launch like a M21 with a 4:11 rear - and then with 5th being 1:1 you can cruise the highway at low RPM. I just put one in my car. Unfortunately had to also swap in the 2.73 gears in the rear

Another advantage - pick up the Nash used for about $800-1200 and you'll keep a lot more money in your pocket compared to the TKO500 swap. It uses the stock driveshaft and a $45 TH400 crossmember.

Just my $.10

Mike

68 Ragtop

· #10 · Mar 21, 2007

Original68fromauntsgarage said:
So then are you saying that the 2:73s may not be so horrible???? It has been a while since I have played with cars and am a bit rusty.........

So let me pose this direction; If YOU had a an M20 and 2:73 gears what would you do?????

Thanks.............................

I have an M20 with 2.73's and it is not so horrible.
I do some freeway driving with that car and no drag racing, so I like it.
If I was going to change anything, it would probably be to a 5 spd to maintain freeway drivability.
If you already have the M20, change the tranny first, drive it then decide.
Just the change from PG to M20 alone is a huge performance gain.

DROPTOPtimes2

· #11 · Mar 21, 2007 (Edited)

I've got 3.55's with an M20 and I think that it's perfect for mostly city and a little highway driving. What's your driving mix? If it's 50% highway, I would do 3.36, if it's mostly city, I'd do 3.55.

Also, what are your motor specs? If you have a high reving motor, it will not like lower gears. Also, you want to think about the power band of your cam.

Use this to get your RPM's for the highway: http://www.classicchevy5speed.com/RPM-Calculator.aspx

Original68fromauntsgarage

Discussion Starter · #12 · Mar 21, 2007

To answer a few of the questions to my questions!!!! LOL

As of right now I have the bone stock 327 210 horse motor with a Rochester 2Bbl on it.

As for the way the engine will be, now that is another story....!!!!:thumbsup:

The plan as of now at least is as follows;

Full motor rebuild to include .030 bore job, forged aluminum pistons to about 9.0-9.5:1, I may or may not stay with the stock heads, depending......

Either way I will get whatever head I use set up hopefully with 202 160 valves, "Beehive" springs, bronze guides and the hardened seats.

Valve train at this point will be Comp cams full roller steel rockers, with one of Comp cams latest set ups the "Thumpr" series roller cam and lifters.

Pete Jackson "quiet" gear drive for that (to me) cool whine...........

Manifold will be a Weiand Stealth (Idle to 6500-6800), with an Edelbrock performer carb in 650 cfm, electric choke.......

MSD 6a spark box, and some type of undetermined high volt coil.

Either Mallory Pro wires, a set of uber thick Taylor's.

My plan is that the motor will be making most / best power after about 1500-1800 rpm through about 5500 ish....I don't want to rev to the moon..........just part way there..........

So, as far as the highway thing goes, I will have it out there quite in- frequently, and the breakdown will be about 75% city (town) and 25% highway during nice weather.

My plan is that Motor combo, with the M20 and 355s will be pretty exhilarating..........

Now keep in mind, I am no Smokey Yunick, (Just dated myself) but I think that should be workable........

Feedback????

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Original68fromauntsgarage

Discussion Starter · #13 · Mar 21, 2007

One more thing.............................

with the 2:73s I have now, will I need a new "Carrier" to accommodate the gear swap???????

Need more info on that.....................

And how tough it is to do.......

You guys are great thanks a lot,

Don

big gear head

· #14 · Mar 22, 2007

big gear head said:
You will need a 3 series differential. I recommend the new 3 series Eaton posi.

Yes, you will need a 3 series. You have a 2 series right now.

327!275hp!Convt!

· #15 · Mar 22, 2007

You could kill 2 or 3 birds with one stone if money is an issue. Buy a 3 ring Saginaw off ebay with the 3.50 first gear & a 1 to 1 final like the Muncie or PG. Its a direct "ez" bolt in. You'll get the off the line performance you want with your 2.73 rear. I know, I know, some people are down on the Saginaw but... some people seem to think they are just fine with horse power not over 350 or so. I've heard & read both good things & bad. Until you build the engine the you described, pay a pretty penny for a good muncie, & spend another grand on the rearend, the 3 ring Saginaw could maybe give you the performance you want (for now)... for a lot less money.

http://cgi.ebay.com/ebaymotors/SAGI...089592268QQcategoryZ33733QQrdZ1QQcmdZViewItem

Here is an article that seems to appreciate the lowly Saginaw:
http://www.camaro-untoldsecrets.com/articles/spotlite2d.htm

DROPTOPtimes2

· #16 · Mar 22, 2007

I've never driven one but i suspect that your rpms will drop quite a bit from first to 2nd and 2nd to 3rd. Just something to consider.

327!275hp!Convt! said:
You could kill 2 or 3 birds with one stone if money is an issue. Buy a 3 ring Saginaw off ebay with the 3.50 first gear & a 1 to 1 final like the Muncie or PG. Its a direct "ez" bolt in. You'll get the off the line performance you want with your 2.73 rear. I know, I know, some people are down on the Saginaw but... some people seem to think they are just fine with horse power not over 350 or so. I've heard & read both good things & bad. Until you build the engine the you described, pay a pretty penny for a good muncie, & spend another grand on the rearend, the 3 ring Saginaw could maybe give you the performance you want (for now)... for a lot less money.

http://cgi.ebay.com/ebaymotors/SAGI...089592268QQcategoryZ33733QQrdZ1QQcmdZViewItem

Here is an article that seems to appreciate the lowly Saginaw:
http://www.camaro-untoldsecrets.com/articles/spotlite2d.htm

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